cyrus-imapd/cyrus-imapd.logrotate

/var/log/imapd.log /var/log/auth.log {
    missingok
    sharedscripts
    postrotate
        /bin/kill -HUP `cat /var/run/rsyslogd.pid 2> /dev/null` 2> /dev/null || true
    endscript
}